Local anesthesia failure in endodontic therapy: the acute inflammation factor.

The attainment of clinically acceptable local anesthesia is often problematic in the treatment of symptomatic pulpitis and symptomatic apical periodontitis. This article reviews the literature to identify the extent of this problem and to understand the organic components involved with this condition. Inflammation, infection, pH changes, alteration in nerve cell membranes, and anatomic variations are all possible causes for failure of local anesthesia during emergency endodontic therapy.